This invention relates to an engine with a valve. More particularly, the invention relates to a gas-pressured engine with a valve.
Typically, needle-less medication injectors use either an expansion spring or a compressed inert gas to propel the fluid medication (via a push rod plunger) through a small orifice (an injector nozzle) which rests perpendicular to and against the injection site. The fluid medication is generally accelerated at a high rate to a speed of between about 800 feet per second (fps) and 1,200 fps (approximately 244 and 366 meters per second, respectively). This causes the fluid to pierce through the skin surface without the use of a needle, resulting in the medication being deposited in a flower pattern under the skin surface.
In a jet injector, if the inert gas is not quickly and properly expelled, fluid may be improperly injected, as with those devices employing a compression spring. Conventional disposable needle-less injectors, such as those shown in U.S. Pat. No. 4,913,699 to Parsons and U.S. Pat. No. 5,009,637 to Newman et al. utilize a gas-containing, breakable tube that is shattered or cracked open by a side mounted trigger. Difficulties arise in the need to maintain tight tolerances on the breakable member, since minor changes in thickness can dramatically effect the pressure needed to deploy the gas from the gas chamber of the device. In addition, the broken shards of the breakable member are ejected at high speed when the gas is expelled and these shards can occasionally jam between the plunger driver and the housing, thereby preventing proper operation of the needle-less injector. Attempts to prevent small shards from being formed would obviate some of this potential, but tend to make activation of the device more difficult.
U.S. Pat. Nos. 6,080,130, 6,063,053, 5,851,198 and 5,730,723 describe needle-less injectors incorporating a gas power source, thus obviating some of the limitations inherent in compression spring injectors and addressing many of the concerns of conventional jet injectors. The injectors described therein have a pre-filled and self-contained compressed gas for providing pressure to inject medication into the skin surface of a patient without the use of a needle.
Gas power sources for needle-less injectors that employ either pop valves or breakaway tab valves to release the inert gas stored in their respective gas chambers, however, may only be opened once, thereby presenting difficulty with regard to quality control testing measures. Additionally, in filling a gas power source with compressed gas, safety measures and a range of quality control features are important. For instance, if a gas power source is critically overcharged, it may rupture during or after filling with a compressed gas. A rupture may occur in storage or even during operation (e.g., during the administration of a needle-less injection). Such an event may result in substantial injury to the recipient of an injection or to an individual administering the same. Other undesirable results may occur when the engine is used in conjunction with a device other than a needle-less injector, including harm to an individual or damage to a device to which such an engine is in operable contact.
It is therefore an object of an embodiment of the instant invention to provide a gas-pressured engine that obviates, for practical purposes, the above-mentioned limitations.
In one embodiment of the instant invention, an engine includes an engine housing and a valve. Compressed gas may be contained in the engine housing, and released upon an opening of the valve. Further, the engine housing may include a depression on one end; the depression imparting to the engine a xe2x80x9cpop-outxe2x80x9d safety feature, wherein, when the engine is critically overcharged, the depression may substantially invert or otherwise deform its shape to provide greater internal volume for the compressed gas. This feature may avoid an engine rupture and may also provide an external visual cue that the engine is critically overcharged.
In another embodiment of the present invention, an engine is fitted with a reusable valve. The valve may contain a rubber head that is held against a fixed element of the engine such that depression of a trigger separates the head from the fixed element, releasing the compressed gas from the engine. A spring may be included in the valve to help maintain a proper airtight seal with the canister holding the compressed gas.